Carcharodontosauridae

Taxobox
name = Carcharodontosaurids
fossil_range = Early-Late Cretaceous

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image_width = 250px
image_caption = "Giganotosaurus" skeleton at the Australian Museum, Sydney
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Saurischia
subordo = Theropoda
infraordo = Carnosauria
superfamilia = Allosauroidea
familia = Carcharodontosauridae
familia_authority = Stromer, 1931
subdivision_ranks = Genera
subdivision = "Acrocanthosaurus"? "Carcharodontosaurus" (type) "Eocarcharia" "Giganotosaurus" "Mapusaurus" "Neovenator"? "Tyrannotitan"

Carcharodontosaurids (from the Greek "Carcharodontosauros": "shark-toothed lizards") were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria. Carcharodontosaurids included some of the largest land predators ever known: "Giganotosaurus", "Mapusaurus", "Carcharodontosaurus", and "Tyrannotitan" all rivaled or exceeded "Tyrannosaurus" in size.

Evolution

Along with the spinosaurids, carcharodontosaurids were the largest predators in the early and middle Cretaceous throughout Gondwana (and Europe, if "Neovenator" is included), and also in North America ("Acrocanthosaurus"). Their ages range from the Barremian (127-121 million years ago) to the Cenomanian (99-93 million years ago). It's possible they were also present during the Turonian (93-89 million years ago).

However, past the Turonian, there seem to be no signs of the presence of these animals anywhere on the world. They were replaced by the smaller abelisaurids in Gondwana and by tyrannosaurids in North America. According to Fernando Novas and colleagues, the disappearance of not only carcharodontosaurids but also spinosaurids and other fauna in both Gondwana and North America seem to indicate that this faunal replacement occurred on a global scale.Novas, de Valais, Vickers-Rich, and Rich. (2005). "A large Cretaceous theropod from Patagonia, Argentina, and the evolution of carcharodontosaurids." "Naturwissenschaften", ]

ystematics

Taxonomy

The family Carcharodontosauridae was originally named by Ernst Stromer in 1931 to include the single newly discovered species "Carcharodontosaurus saharicus". A close relative of "C. saharicus", "Giganotosaurus", was added to the family when it was described in 1995. Additionally, many paleontologists have included "Acrocanthosaurus" in this family (Sereno et al. 1996, Harris 1998, Holtz 2000, Rauhut 2003), though others place it in the related family Allosauridae (Currie & Carpenter, 2000; Coria & Currie, 2002). "Neovenator" may also be a member of the Carcharodontosauridae (Rauhut, 2003; Holtz "et al.", 2004).

With the discovery of "Mapusaurus" in 2006, Rodolfo Coria and Phil Currie erected a subfamily of Carcharodontosauridae, the Giganotosaurinae, to contain the most advanced South American species, which they found to be more closely related to each other than to the African and European forms. Coria and Currie did not formally refer "Tyrannotitan" to this subfamily, pending a more detailed description of that genus, but noted that based on characteristics of the femur, it may be a giganotosaurine as well.Coria, R.A., and Currie, P.J. (2006). "A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina." "Geodiversitas", 28(1): 71-118.]

* Family Carcharodontosauridae
** Genus "Acrocanthosaurus"
** Genus "Carcharodontosaurus"
** Genus "Eocarcharia"Sereno, P.C. and Brusatte, S.L. 2008. " [http://www.app.pan.pl/acta53/app53-015.pdf Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger] ". "Acta Palaeontologica Polonica 53" (1): 15–46.]
** Genus "Neovenator"
** Genus "Tyrannotitan"
** Subfamily Giganotosaurinae
*** Genus "Giganotosaurus"
*** Genus "Mapusaurus"

Phylogeny

In 1998 Paul Sereno defined Carcharodontosauridae as a clade, consisting of "Carcharodontosaurus" and all species closer to it than to either "Allosaurus", "Sinraptor", "Monolophosaurus", or "Cryolophosaurus". Therefore, this clade is by definition outside of the clade Allosauridae.

clade| style=font-size:100%;line-height:80%
label1=Carcharodontosauridae
1=clade
1="Carcharodontosaurus"
label2=Giganotosaurinae
2=clade
1="Giganotosaurus"
2="Mapusaurus"
Cladogram after Coria and Currie, 2006

The placement of "Acrocanthosaurus" and "Neovenator" is unclear, with some researchers favoring Carcharodontosauridae and others favoring Allosauridae. "Bahariasaurus" has also been proposed as a carcharodontosaurid, but it's remains are too scarce to be certain. It appears to be synonymous with the ceratosaur "Deltadromeus".

Carcharodontosaurids have been proposed as more closely related to abelisaurids, as opposed to the allosaurids. This is due to these two clades sharing some cranial features (see link below). However, these similarities appear to derive from parallel evolution between these two groups. A larger number of cranial and postcranial characters support their relationship with allosaurids.

References

External links

* [http://www.dinodata.org/index.php?option=com_content&task=view&id=1030&Itemid=104 Carcharodontosauridae at Dinodata]
* [http://www.dinodata.org/index.php?option=com_content&task=view&id=9356&Itemid=164 Carcharodontosaurid cranial anatomy at DinoData]
* [http://home.comcast.net/~eoraptor/Carnosauria.htm#Carcharodontosauridae Carcharodontosauridae at Theropod Database]
* [http://dml.cmnh.org/1999Mar/msg00493.html Carcharodontosauridae/Abelisauridae]
* [http://dml.cmnh.org/1999Mar/msg00504.html Carcharodontosauridae/Abelisauridae 2]